Improvement in bridges



OFFICE c 'MAPRV'EMEFNT."NBRf'PeES-"f f j "sptsfaaanffmagpar@instantes,N0,1ron,s55,jqaeaAugusta,1810-.

T o allwh'om it may concern: Q l ,KN Be it known that VLTHOMAS W. Mos'ii;4 LEY, of Boston, in thev coun'typof Suffolk 'and State 'of Massachusetts, have yinvent'edfan lIniproved Bridge, of which the following is a specification: v l.

My invention is a combination of the mechanical elements or features which occur singly or in various minorV 'combinations in bridges. These elements, as they may be termed, are the king-post, truss, arch, and girder, the object being to avail the use of all in a structure, to which each shall impart its distinguishing characteristics and valuable quality.

In the accompanying drawing, Figure l is a side elevation of a bridge constructed after my plan, and including about three-quarters of the span. Fig. 2 is a sectional view, on an enlarged scale, of the bridge, on the dotted line a, b, Fig. 1. Fig. 3 is a view, on a scale larger than that of Fig. 1, of one of the ends of the structure, which form the side of a bridge. Fig. 4 is a perspective view ol that portion of the structure in the vicinity of the foot ot' the king-post.

The structure which forms one side of the bridge consists, in the main, of A A, a pair of inclined beams, which meet at the middle of the span, and are stepped against footplates C, resting on sole-plate D on the abutments E. (The ends ofthe bridge are similar, and but one is shown in the principal figure.)

b b is an arch, which is secured to the two beams, and springs from the sole-plates D on the respective abutments; G, a -girder or chord, which unites the foot-plates O and soleplates D, and thus sustain the thrust, and acting as a chord to the arch; H, a king-post, which forms the middle vertical member of the truss, connecting the beams at their junction with the girder or chord at its mid-length. 1, a tension-rod, connecting the haunches of the arch b b' with the foot ot' the king-post H; K K, &c., suspension-rods from the beams A A, to support the girder or chord and the track-sleepers.

. stiftenedbyhangle-iron,a'Sfai on its sides at the uppervedge, and riveted thereto. These tinf plates rise at an angl'e varyingrfroml six to twentyftwo degrees, as l.may be needed, and are the equivalents of the beams or braces in a king-.90st bridge,'.or the principal rafters in a roof-truss.v The foot of the iin-plate rests against the foot-plate C, whichcorresponds in function to a skew-back or thrust-block. The foot-plate rests upon and is secured to a soleplate of shoe D, which also receives the springing ofthe arch b b and the end of the girder Gr, as will be presently described. The iron iin-plate a varies in thickness as the span ofthe arch and the expected burden may require, say, from one-eighth ot' an inch to one inch or more in thickness, and in width to make a chord to half the arch b b', and to repsent on the back of the latter two tangents, meeting at the haunch.

Unsupported, this iin-plate, even with the stift'ening of angle-iron on the upper edge, lacks the lateral rigidity to make it serviceable as a thrust-beam; and this brings me to the descriptionot' the arch b b', which is made of upright angle-iron, l-ron, or Z-iron, which 'is preferably ofthe form best seen in Figs. 2

and 3.

The plate, as shown, has two iianges, b b', united by a' web, b, the langes being vertical, and the web following the camber of the arch. A pair of such angle-irons is riveted to the ns ofthe thrust-beams A A, one on each side of the latter. The angle-plates forming the arch vary in thickness and width with the span and expected burden of the bridge, being, say, from onefourth inch to two inches or more in thickness, and from three inches to two feet or more in Width. They are riveted through and through on each side of the iinplate, as shown in Fig. 2. The shoe-plate D receives the springing of the arch, and has a turned-up toe, d, against which the heel oi' the arch thrusts.

lhe girder G forms the chord of the arch b b', and also prevents the spreading of the feet of the beams or iin-plates A A. Each girder is made of Hat-bar, flat-plate, or angle-iron, and preferably of the latter, as clearly seen in Fig. 3, the shaped irons being laid with their vertical flanges back to back, and riveted together at intervals. At their ends these girders or chords embrace between them the footplate C, to which they are securely riveted. The horizontal ianges of these grders or chord-bars are likewise riveted to the soleplate D, some of the rivets being seen at g g, Fig. 3.

I have now described the elements consisting ofthe inclined beams, the arch, and the girder. The angle-plate arch being added to each side of the iin-plates A, keeps the latter in perfect line, and they then exert their full strength, and each becomes a chord to onehalf of the arch, strengthening the latter, especially at its haunches.

H is an iron king-post, preferably formed of two T-bars, h h, with their faces together, as seen in Fig. 4. These extend from the beam A above to the girder-plates Grv beneath, and are made fast to each.

I I are tension-rods, one on each side of the bridge-truss. These are attached at their ends to the ribs of the plates A A, pass obliquely downward to or nearly to the girder G, and take hold of the foot of the king-post, which is then utilized as a strut in the support of the apex of the compound beam and the crown of the arch, the two being practicably coincident as to position. This straining-rod has notch, cut, or gib, to prevent its slipping when the'loady or burden is thrown on the haunch of the arch.

The suspension-rods K are similar to those in other bridges, and depend from the iinplate, to support the girders or chords G and the sleepers of the road-bed, as shown at Fig. 2. 

